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CREATE TABLE t1 (f0 INT KEY AUTO_INCREMENT, f1 INT, f2 INT);
CREATE TABLE t2 (f0 INT KEY AUTO_INCREMENT, f1 INT, f2 INT) ENGINE=MYISAM;
CREATE TABLE t3 (f0 INT KEY AUTO_INCREMENT, f1 INT, f2 INT, KEY (f0), KEY (f1), KEY (f1, f2));
INSERT INTO t1 (f1, f2) VALUES (1,1 ),(2,2),(3,3),(4,4);
INSERT INTO t1 (f1, f2) SELECT f1, f2 FROM t1;
INSERT INTO t1 (f1, f2) SELECT f1, f2 FROM t1;
INSERT INTO t1 (f1, f2) SELECT f1, f2 FROM t1;
INSERT INTO t2 (f1, f2) SELECT f1, f2 FROM t1;
INSERT INTO t3 (f1, f2) SELECT f1, f2 FROM t1;
DELETE FROM t1 WHERE f1=1;
DELETE FROM t2 WHERE f1=1;
ANALYZE TABLE t1;
Table Op Msg_type Msg_text
test.t1 analyze status OK
ANALYZE TABLE t2;
Table Op Msg_type Msg_text
test.t2 analyze status OK
ANALYZE TABLE t3;
Table Op Msg_type Msg_text
test.t3 analyze status Table is already up to date
SELECT COUNT(*) FROM t1;
COUNT(*)
24
SELECT COUNT(*) FROM t2;
COUNT(*)
24
SELECT COUNT(*) FROM t3;
COUNT(*)
32
Case 1: IS query uses mysql.table_stats to read dynamic table statistics
SET SESSION information_schema_stats_expiry=default;
SELECT table_rows, avg_row_length, data_length, max_data_length, index_length,
data_free, auto_increment, checksum, update_time, check_time
FROM information_schema.tables WHERE table_name in ('t1', 't2');
TABLE_ROWS AVG_ROW_LENGTH DATA_LENGTH MAX_DATA_LENGTH INDEX_LENGTH DATA_FREE AUTO_INCREMENT CHECKSUM UPDATE_TIME CHECK_TIME
24 13 416 3659174697238527 2048 104 33 NULL # NULL
24 13 416 3659174697238527 2048 104 33 NULL # NULL
SELECT * FROM information_schema.statistics WHERE table_name='t3'
ORDER BY index_name, seq_in_index;
TABLE_CATALOG TABLE_SCHEMA TABLE_NAME NON_UNIQUE INDEX_SCHEMA INDEX_NAME SEQ_IN_INDEX COLUMN_NAME COLLATION CARDINALITY SUB_PART PACKED NULLABLE INDEX_TYPE COMMENT INDEX_COMMENT IS_VISIBLE EXPRESSION
def test t3 1 test f0 1 f0 A 32 NULL NULL BTREE YES NULL
def test t3 1 test f1 1 f1 A 4 NULL NULL YES BTREE YES NULL
def test t3 1 test f1_2 1 f1 A 4 NULL NULL YES BTREE YES NULL
def test t3 1 test f1_2 2 f2 A 4 NULL NULL YES BTREE YES NULL
def test t3 0 test PRIMARY 1 f0 A 32 NULL NULL BTREE YES NULL
Case 2: IS query uses UDF's to read dynamic table statistics
SET SESSION information_schema_stats_expiry=0;
SELECT table_rows, avg_row_length, data_length, max_data_length, index_length,
data_free, auto_increment, checksum, update_time, check_time
FROM information_schema.tables WHERE table_name in ('t1', 't2');
TABLE_ROWS AVG_ROW_LENGTH DATA_LENGTH MAX_DATA_LENGTH INDEX_LENGTH DATA_FREE AUTO_INCREMENT CHECKSUM UPDATE_TIME CHECK_TIME
24 13 416 3659174697238527 2048 104 33 NULL # NULL
24 13 416 3659174697238527 2048 104 33 NULL # NULL
SELECT * FROM information_schema.statistics WHERE table_name='t3'
ORDER BY index_name, seq_in_index;
TABLE_CATALOG TABLE_SCHEMA TABLE_NAME NON_UNIQUE INDEX_SCHEMA INDEX_NAME SEQ_IN_INDEX COLUMN_NAME COLLATION CARDINALITY SUB_PART PACKED NULLABLE INDEX_TYPE COMMENT INDEX_COMMENT IS_VISIBLE EXPRESSION
def test t3 1 test f0 1 f0 A 32 NULL NULL BTREE YES NULL
def test t3 1 test f1 1 f1 A 4 NULL NULL YES BTREE YES NULL
def test t3 1 test f1_2 1 f1 A 4 NULL NULL YES BTREE YES NULL
def test t3 1 test f1_2 2 f2 A 4 NULL NULL YES BTREE YES NULL
def test t3 0 test PRIMARY 1 f0 A 32 NULL NULL BTREE YES NULL
SET SESSION information_schema_stats_expiry=default;
DROP TABLE t1;
DROP TABLE t2;
DROP TABLE t3;
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